Client Applications Must Now Support SNI
On June 29, 2016 we migrated all of our services to a new hosting infrastructure.
During this migration, we implemented a SSL Virtual Hosting logic for associating multiple IP addresses (corresponding to our different servers) to a single SSL certificate. To accomplish this we used the extension SNI (Server Name Indication) TLS protocol.
However, this requires that the client applications that make requests to our servers support the SNI extension.
Case 1: outdated browsers wishing to visit Sellsy
Solution: You must update the browser to resolve this issue. However, IE in Windows XP is does not support the SNI extension, so it will be necessary to update your browser or operating system.
Case 2: client applications using our API
Solution: You must update the server application by installing a version that supports SNI.
For more information, we recommend you read this article that explains the function of the SNI extension as well as the browser and server applications that support it.